Paper machine press

ABSTRACT

A PRESS SECTION HAS A DRIVEN SUCTION PRESS ROLL AND A SMALL DIAMETER PRESS ROLL LOCATED WITHIN AN ENDLESS FELT, AND EACH PRESS ROLL FORMS A NIP WITH THE SAME THIRD PRESS ROLL LOCATED OUTSIDE THE FELT. THE SMALL DIAMETER PRESS ROLL IS ROTATABLY SUPPORTED WITHIN A CRADLE FORMED BY A PLURALITY OF BACKUP ROLLERS WHICH ARE MOVEABLE TO RETRACT THE PRESS ROLL TO A POSITION WHERE IT IS DRIVEN SOLELY BY THE FELT AND PERMITS THREADING OF A PAPER WEB WITHOUT DAMAGING THE FELT.

W. C. NOTBOHM ET AL PAPER MACHINE PRESS Feb. 23, 1971 Filed June 10, 1968 v 2 Sheets-Sheet 2 United States Patent 3,565,759 PAPER MACHINE PRESS Willard C. Notbohm, Walter E. Rojecki, and Paul M. Schalfrath, Watertown, N.Y., assignors to The Black Clawson Company, Hamilton, Ohio, a corporation of Ohio Filed June 10, 1968, Ser. No. 735,821 Int. Cl. D21f 3/00 U.S. Cl. 162-358 14 Claims ABSTRACT OF THE DISCLOSURE A press section has a driven suction press roll and a small diameter press roll located within an endless felt, and each press roll forms a nip with the same third press roll located outside the felt. The small diameter press roll is rotatably supported within a cradle formed by a plurality of backup rollers which are movable to retract the press roll to a position where it is driven solely by the felt and permits threading of a paper web without damaging the felt.

BACKGROUND OF THE INVENTION In a paper machine press assembly as disclosed in Rojecki Pat. No. 3,331,734 which issued to the assignee of the present application, a small diameter press roll is supported to form a high intensity nip with a substan tially larger diameter press roll. Many of these press assemblies have proved very successful and are giving highly satisfactory results. Other installations, however, have presented some problems. For example, air always tends to be carried into the nip by entrainment along the face of the large diameter press roll, and if this entrained air is entrapped between the web and the felt, it may result in sheet blowing which can cause defective paper due to wrinkles, holes or breaks which reduce machine efficiency.

Another problem arises from the substantial wedge angle at the inlet of the nip resulting from the small diameter press roll, which tends to reject the wads or lumps of paper sometimes associated with the leading end of the web during the initial threading operation, causing such wads and lumps to pile up ahead of the nip. Then, when the wads and lumps do pass through the nip, the high intensity nip pressure sometimes causes them to cut and mark the felt so that the felt has to be replaced.

One method of reducing the above problem of cutting or marking the felt is to incorporate a high speed kicker roll ahead of the high intensity nip and adjacent the web so that any wads and lumps are kicked off the felt and the leading end of the web before it enters the press nip. Such a roll, however, doesnot solve the problem of blowing caused by the entrapment of air between the web and felt.

SUMMARY OF THE INVENTION The present invention is directed to an improved paper machine press which solves the aforementioned problems of blowing the web and cutting or marking of the felt passing through the high intensity nip and effectively protects the felt during threading of a newly formed paper web through the press. In accordance with one embodiment of the invention, a suction press roll is positioned within an endless felt and forms a nip with a second press roll located outside the felt. A third press roll having a diameter substantially smaller than the diameters of the first and second press rolls is also located Within the felt and forms a second nip with the second press roll. The small diameter press roll is supported for movement into and out of nip-forming relation with the suction roll.

3,565,759 Patented Feb. 23, 1971 l ce The newly formed web is carried by the felt and into the first nip formed with the suction roll so that air between the web and felt are removed and any wads or lumps are crushed. Prior to threading the web, however, the third or small diameter press roll may be retracted from the second press roll so that the lead end of the paper web is carried through the open nip without any danger of cutting or marking the felt. After the web is threaded, the small diameter or third press roll can be pressure loaded to form a high intensity nip with the second press roll, but while in its retracted position, the third press roll is driven at web speed by the felt so that when the high intensity nip is formed, there is no inertia shock produced by the third press roll on the felt to cause marking or cutting of the felt.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary elevational view of a paper machine press constructed in accordance with the invention;

FIG. 2 is a view taken generally along the line 2-2 of FIG. 1 with the center portion broken away;

FIG. 3 is an enlarged fragmentary section taken generally on the line 33 of FIG. 2;

FIG. 4 is a section taken generally on the line 4-4 of FIG. 1 with the center portion of the press broken away; and

FIG. 5 is an enlarged fragmentary and somewhat schematic section taken generally on the line 5-5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the frame includes a pair of parallel spaced base members 12 each supporting a bearing 13. A suction press roll 15 has journals supported by the bearings 13 and includes the usual cylindrical shell 16 (FIG. 5) having multiple perforations 18, and which also may have a rubber cover (not shown). A suction box 20 is located within the upper portion of the press roll 15 and is connected to a suction line (not shown) which enters the press roll through one of its journals. The machine drive 22 (FIG. 1) is connected to the other journal for driving the roll 15, and a semi-cylindrical saveall pan 23 extends between the bearings 13 around the lower portion of the suction press roll 15.

The frame 10 also includes parallel spaced side members 24 which are rigidly secured to the base member 12. A pair of parallel spaced arms 25 are positioned between the frame members 24 and are rigidly connected by a laterally extending plate 26 and a shaft 27 which is rotatably supported by aligned bearings 28 mounted on the frame members 24.

An upper or second press roll 30 has journals which are supported by bearings 32 located within U-shaped end portions 33 of the arms 25 and secured by screws 34. The press roll 30 has a hard smooth outer surface 35 which is continuously cleaned by a blade 38 of a doctor assembly 40 including a blade support frame 41 mounted on a shaft 42 pivotally supported by bearing blocks 43 mounted on the plate 26 connecting the arms 25. The doctor blade 38 is retracted from the surface 35 by actuation of a lift cylinder 45 which is mounted on one of the bearings 32 and has a plunger 46 adapted to engage a pivot arm 47 connected to the shaft 42.

A pair of cylinders 50 are pivotally mounted on the base members 12 of the frame 10 by pins 51 and have piston rods 52 pivotally connected to the arms 25 by pins 53. By actuation of the cylinders 50, the press roll 30 is moved into pressure engagement with the suction press roll 15 to form a nip N; at approximately a five oclock position on the roll 30. A helper drive 55 may be connected to one of the journals of the press roll 30 through a shaft 56 (FIG. 4) although in most installations, the press roll 30 can be driven solely through the nip N by the suction press roll and its drive 22.

A press roll 60 (FIG. 1) forms a second nip N with the press roll at approximately a seven oclock position and has an outer diameter substantially smaller than the diameters of the press rolls 15 and 30 for obtaining a high intensity pressure within the nip N Referring to FIG. 5, the press roll includes journals 61 and may be a solid or tubular roll, preferably formed of stainless steel. The small press roll 60 is also preferably provided with a suitably grooved surface as described and for the same reasons pointed out in the above patent. For some installations, however, particularly at such locations on the paper machine where the water content of the web has been substantially reduced, it may be found satisfactory to utilize a smooth surfaced small roll 60. It is also possible to form the roll 60 as a metal core with a cover of resilient or elastomeric material. In such case, since many resilient or elastomeric materials are either thermally sensitive or are subject to internal heat buildup due to hysterisis of the material itself, it may be desirable to cool the metal core through the introduction of a cooling medium, such as water, to dissipate this heat. Provision can be made to introduce and remove such cooling media through hollow journal 61 and rotary joints on small press roll 60.

The press roll 60 is supported by a cradle assembly which includes a cross beam 72 (FIGS. 1 and 4) having a top flange 73 (FIG. 3) and reinforcing side plates 74. Brackets 76 (FIG. 4) are rigidly secured to the ends of the beam 72 and are releasably attached to bosses 77 on the U-shaped portions 33 of the arms 25 by a series of eye-bolts 78. The bolts 78 are pivotally connected to the bosses 77 and extend through corresponding slots '79 formed with the brackets 76.

The cradle assembly 70 further includes a series of rollers (FIGS. 2 and 5) which are arranged in an alternately staggered manner in two rows to define a nest or cradle for the press roll 60. For a detailed description of the specific construction of the rollers 85, reference is made to copending application Ser. No. 623,732, filed Mar. 16, 1967, now abandoned, and assigned to the assignee of the present invention. Each roller 85 is mounted on a shaft 87 (FIG. 5) which is supported within aligned V-shaped notches 88 formed within upwardly projecting ears 89 of a bracket 90, and screws 91 secure each shaft 87 to its supporting ears 89. Each bracket is pivotally mounted on a shaft 92 which is supported by ears (not shown) projecting upwardly from a flat plate 93 secured to the top flange 13 of the cross beam 72.

An elongated resilient air spring or air bag is positioned between each row of support brackets 90 and the plate 92 so that by controlling the air pressure within the air bags 100, the brackets 90 are pivoted with uniform pressure to move the press roll 60 between a retracted position as shown in FIG. 5 and a position forming a high intensity nip N as shown in FIG. 1. While the high intensity press roll 60 is primarily supported by the rollers 85, each journal 61 of the press roll 60 is received within an anti-friction bearing 102 (FIGS. 1 and 3) which is guided for floating movement in a radial direction by parallel spaced retaining bolts 103 projecting upwardly from a housing 105 mounted on the plate 92. A bar 106 and nuts 107 rigidly connect the upper ends of the bolts 103. i

An endless felt F is directed through the nips N and N and extends downwardly around a series of felt guide rolls 110 (FIG. 1) so that the suction press roll 15 and the small diameter press roll 60 are located within the felt F and the press roll 30 is located outside or above the felt. The press roll 60 is wrapped a few degrees by the felt F which is provided with a Controlled tension by biasing one of the felt guide rolls 110 with suitable air cylinders (not shown).

A pair of adjustable legs 112 (FIG. 1) are provided on each end of the beam 72 so that when it is desired to replace the felt F, the cradle assembly 70 is elevated by pivoting the arms 25, and spacer blocks 113 are positioned on the frame 10 under the legs 112. The cradle assembly 70 is lowered so that the legs rest upon the blocks 113, after which the eye-bolts 78 are released and swung upwardly to disconnect the cradle assembly 70 from the support arms 25. The top press roll 30 is then elevated to allow the felt F to be conveniently inserted into both of the nips N and N In operation, when the leading end of a newly formed paper web W is to be directed through the press of the invention, the pressure within the air bags 100 is reduced so that press roll 60 is moved to a retracted position, thereby opening nip N The leading end of the paper web W is carried by the felt F through the first closed suction nip N and then through open nip N After the web W is threaded, the pressure within the air bags 100 is increased to move press roll 60 into pressure engagement with the top press roll 30 and thereby to form the second nip N of high intensity pressure.

As shown in FIG. 1, when the web W exits from the nip N the web is directed upwardly away from the felt F over a paper guide roll 115' so that sheet rewetting through contact with the felt on the exit side of nip N is avoided. Water thrown or sprayed from the outgoing nip N inside the felt is prevented from rewetting the felt by the vertical splash guard 116.

As mentioned above, a paper machine press constructed in accordance with the invention provides several desirable features and advantages. For example, by arranging both the suction roll 15 and small diameter press roll 60 within the endless felt F, and by supporting the press roll 60 so that it can be retracted to open the high intensity nip N the web W can be easily threaded through the press without any danger of marking the felt or blowing the web. That is, when the tail or leading end of a newly formed paper web W is picked up by the felt F, it is first carried through the wide suction nip N where any lumps or wads are crushed and the air carried into the nip by roll 30 is removed by the suction press roll 15 to prevent blowing of the web. After the lead end of the web with the crushed wads and lumps have passed through the open nip N the press roll 60 is elevated to form the high intensity nip N Moreover, there is no danger of marking or cutting the felt by inertia shock from the press roll 60 since this roll has low mass and is continuously driven while in its retracted position by the felt F so that the roll has a surface speed substantially the same as the felt F.

The support of the top press roll 30 and the cradle assembly 70 for the high intensity press roll 60 also provide an important feature of the invention. That is, with both the top press roll 30 and the cradle assembly 70 mounted on the pivotable arms 25, the endless felt F may be conveniently replaced simply by lowering the cradle assembly 70 onto the blocks 113 and disconnecting the cradle assembly by releasing the swing bolt 78. This permits the top press roll 30 to be raised above both the suction press roll 15 and the press roll 60 resting on the cradle assembly 70.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A paper machine press for use in combination with an endless felt for dewatering a paper web carried by the felt, comprising a first press roll positioned within the felt, a second press roll positioned outside the felt and forming a first nip with said first press roll, a third press roll positioned within the felt and having a diameter substantially smaller than the diameters of said first and second press rolls, means supporting said third press roll for movement between a position forming a second nip with said second press roll and a retracted position spaced from said second press roll, means for directing the felt through said first and second nips and partially around said third press roll, and means for driving at least one of said first and second press rolls causing the felt to carry the web successively through said first and second nips as well as to drive said third roll in said retracted position thereof.

2. A press as defined in claim 1 wherein said first press roll is a suction roll for removing both moisture and air within said first nip.

3. A press as defined in claim 1 wherein said third press roll comprises a cylindrical metal core, and a resilient layer surrounding said core.

4. A press as defined in claim 1 wherein said means supporting said third press roll include a plurality of rollers arranged in two rows to define a cradle for receiving said third press roll, a movable bracket for supporting each said roller, and fluid pressure means for moving each said bracket to provide a controlled uniform pressure within said second nip.

5. A press as defined in claim 1 including a pair of arms supporting said second press roll, pivot means supporting said arms, pressure cylinder means connected to said arms for moving said second press roll relative to said first press roll, and means for connecting said supporting means for said third press roll to said arms to provide for movement of said third press roll with said second press roll.

6. A press as defined in claim 1 wherein the axes of said first and third press rolls are positioned below said second press roll on opposite sides of a vertical plane extending through the axis of said second press roll.

7. A press as defined in claim 1 wherein said means supporting said third press roll include a plurality of rollers arranged to define a cradle for receiving said third press roll, fluid actuated means for supporting said rollers, said third press roll having journals at the ends thereof, a bearing mounted on each said journal, and means retaining each said bearing for floating movement.

8. A paper machine press for use in combination with an endless felt supporting a paper web on the outer surface thereof, comprising a first press roll positioned within the felt, a second press roll positioned outside the felt, means for urging said rolls into pressure engagement defining a first nip having an entry side and an exit side for the felt, a third press roll positioned within the felt in spaced relation with the exit side of said nip, said third press roll being of relatively small diameter in comparison with the diameters of said first and second press rolls, means supporting said third press roll for movement in a predetermined range between a position forming a second nip with said second press roll and a retracted position spaced out of engagement with said second press roll, means maintaining the felt in sufiicient tension to drive said third press roll in all positions of said third press roll within said range of movement thereof, and means for driving said first press roll to drive said second press roll and the felt through pressure engagement therewith.

9. A paper machine press for use in combination with an endless felt for dewatering a paper web carried by said felt, comprising a first press roll positioned outside the felt, a second press roll positioned within the felt and having a diameter substantially smaller than the diameter of said first press roll, means supporting said first press roll for displacement to a position spaced from said second press roll, means including a plurality of rollers arranged to define a cradle for rotatably supporting said second press roll, means connecting said supporting means for said second press roll to said supporting means for said first press roll to cause displacement of said second press roll with said first press roll, means for moving said rollers relative to said first press roll to move said second press roll between a position forming a nip with said first press roll and a retracted position spaced from said first press roll, means for directing said endless felt through said nip and partially around said second press roll and means for driving said first press roll and said felt to effect driving of said second press roll in said retracted posi tion by said felt.

10. A press as defined in claim 9 wherein said means supporting said second press roll further include a bracket for each said roller, pivot means disposed substantially within a plane defined by the axes of said first and second press rolls for supporting each said bracket, and fluid actuated means for pivoting said brackets to move said second press roll between said nip and retracted positions.

11. A press as defined in claim 10 wherein said fluid actuated means comprise at least one elongated air bag positioned adjacent a plurality of said brackets.

12. A paper machine press for use in combination with an endless felt for dewatering a paper web carried by the felt, comprising a first press roll positioned within the felt, a second press roll positioned outside the felt and forming a first nip with said first press roll, a third press roll posi tioned within the felt and having a diameter substantially smaller than the diameters of said first and second press rolls, means including a plurality of rollers arranged to define a cradle for rotatably supporting said third press roll, fluid pressure means for supporting said rollers in position to form a second nip between said third press roll and said second press roll, means for directing the felt through said first and second nips, and means for driving at least one of said first and second press rolls causing the felt to carry the web successively through said first and second nips.

13. A paper machine press for use in combination with a looped endless felt for dewatering a paper web carried by the felt, comprising a suction rol'l positioned within the loped felt, a press roll positioned outside the felt and forming a first nip with said suction roll, means positioned within the felt and having a curved surface forming a second nip with said press roll, said surface having a radius of curvature substantially smaller than the radius of curvature of the outer surface of each of said rolls, means for directing the felt through said first and second nips, and means for driving at least one of said rolls to cause the felt to carry the web successively through said first and second nips.

14. A press as defined in claim 13 including fluid pressure means for moving said curved surface between a retracted position and a position forming said second nip.

References Cited UNITED STATES PATENTS 1,810,102 6/1931 Faber 170X 2,415,351 2/ 1947 Hornbastel et al. 162-358X 3,017,930 1/1962 Dunlap 162352 3,035,512 5/1962 Beachler 100170X REUBEN FRIEDMAN, Primary Examiner T. A. GRANGER, Assistant Examiner 

